How to move Project Sub-Task to another Parent-Task

We have business requirement where As part of the new task restructuring for projects module, we need to move subtasks from one parent to another. We were able to update existing tasks (both parent and child) and add new tasks (both parent and child). However, we are unable to move tasks from one parent to another using FBDI.Could you please advise on this, if it is possible or what is the best way to do it